Top 10 steel skyscrapers

There was a time when building skyscrapers with steel as the main structural element was core to constructing tall buildings. It wasn't until the 1960s that a vibrant young engineer of Bengali descent entered the fray and offered systems to allow skyscrapers to reach new heights.

By Stuart Matthews

Sat 02 Oct 2010 04:00 AM

There was a time when building skyscrapers with steel as the main structural element was core to constructing tall buildings. It wasn't until the 1960s that a vibrant young engineer of Bengali descent entered the fray and offered systems to allow skyscrapers to reach new heights.

The late Fazlur Khan is considered as the father of modern skyscraper design. His tubular structural engineering designs, first introduced while he was working at Skidmore Owings and Merill's Chicago office, quickly transformed the city's skyline. Most US buildings over 40-storeys high constructed since the 1960s now use a tube design derived from Khan's structural engineering principles.

There are three variations of Khan's tube design. The Framed Tube is the simplest and can be adapted to square, rectangular, circular and freeform shapes. The Trussed Tube or Braced Tube design uses fewer and more widely spaced exterior columns, which are tied together with external bracing, while the Bundled Tube consists of several buildings tied together to resist lateral forces.

The beauty of Khan's tubular systems is that buildings can be constructed using steel or concrete, or a composite of the two, to reach lofty heights. In fact, the Burj Khalifa - coincidentally designed by Skidmore Owings and Merill - used a bundled tube design and a composite of steel and concrete to hit its record 828 metres. Proportionally, the design uses half the amount of steel used in the construction of the Empire State Building thanks to the tubular system.

The following list has been drawn up using data gathered by the Council of Tall Buildings and Urban Habitat. We've not counted current construction projects, or proposed buildings, nor have we included freestanding masts or towers - they are incuded in a list of their own.

We've also used the Council's definition for steel towers, where the main construction vertical and lateral structural elements and floor systems are constructed from steel.

As the construction industry is an ever-evolving one, the list will change as more projects are completed over time. Even in Dubai itself, there are projects that will make this list before the year is out.

Willis Tower (formerly the Sears Tower)

America's building boom tailed off during the 1970s, but not before the monolithic Sears Tower was erected in Chicago. Using Khan's Bundled Tube structural engineering principles, the building takes its strength from the combination of nine main structures arranged in a three by three grid that make up the impressive complex.

It's a clever arrangement. All towers rise to 50-storeys, where the northeast and southwest buildings stop. The remaining seven towers continue to the 66th floor where the northeast and southwest structures end, and at 90-storeys, the north, south and east floors top out. The two remaining towers, the west and central towers, then stretch to 110 floors, the building's top. A similar system of bundled towers was used by SOM to construct the Burj Khalifa.

Work started on construction of the Sears Tower in 1970 and the building was finished three years later. It has received numerous design and structural awards since its 1973 inauguration, and remains a defining development for mega structures which have followed since.

The Sears naming rights ran out in 2003 and in 2009, London-based insurance broker Willis Group Holdings agreed to lease a portion of the building and take over the naming rights.

The building's owners last year commissioned SOM to install 10ft square and four foot deep glass viewing balconies on the Skydeck at the 103rd floor that offer staggering five-sided views from the tower - at a height of 1353ft. The boxes are mounted within a steel frame and can be retracted back in to the building for cleaning.

It goes without saying that The Empire State Building is the most iconic skyscraper ever built. Whether its legend was sealed with scenes of a giant ape battling bi-planes with one hand while cradling Fay Wray in the other, or by its enduring status as the tallest building in New York (post World Trade Centre), the Empire State Building is the one sight most visitors to the city have at the top their lists.

The art deco building set new benchmarks for construction when it was completed in 1931, and it held the title of world's tallest building for over 40 years before being eclipsed by the World Trade Centre in 1972.

The building's history is as interesting as the project itself. Financed by John J Raskob, a former DuPont (hired by Pierre Du Pont himself) and GM vice president (he engineered DuPont's 43% ownership of GM), the building was designed by architects Shreve, Lamb and Harmon Associates. One version of the story is that Raskob stood a pencil on its end and asked William F Lamb, "Bill, how high can you make it so that it won't fall down?"

As it turned out, that ended up being 381m. The steel-framed structure was built in record time (13 months), mainly fuelled by the need to get the building up during the depression so that the developer could start renting out floorspace - and partly because the Empire State Building was in race with the Chrysler building to gain worldwide recognition as the tallest building. Contractors Starrett Brothers and Eken fast tracked the project through meticulous planning and it was opened by US president Herbert Hoover on May 1 1931.

Originally commissioned by Standard Oil of Indiana, the building uses a tubular steel frame structure to support itself and provide the building with its weather and earthquake resistant properties.

Designed by the late Edward Durell Stone, the 88-storey skyscraper is the third tallest building in Chicago (behind the Sears and Trump towers) and third tallest all-steel building in the world. Built between 1970 and 1972 by Turner Construction (now a subsidiary of Hochtief), the building also held the record for the tallest marble clad tower.

Turner Construction is well known throughout the Middle East: the company acted as project managers on the Burj Khalifa and has also been involved in the Al Hamra Tower project in Kuwait City, Emirates Palace Hotel in Abu Dhabi and Al Faisaliyah Centre in Riyadh, Saudi Arabia.

Like the Willis Group which has naming rights on the tallest tower in Chicago, Aon is an insurance brokerage firm. The company specialises in risk management services, insurance and reinsurance brokerage. The Aon Centre is the company's global headquarters.

Though it only stands as the fifth tallest tower development in Hong Kong, The Centre is one of the very few buildings in the city that is constructed entirely out of steel.

Dennis Lau & Ng Chun Man Architects & Engineers (HK) Ltd designed the building, with structural engineering services provided by Maunsell AECOM Group. The structure was started in 1995 and finished three years later by main contractors Paul Y ITC Construction.

The building has 73 floors and is currently listed as the 22nd tallest building in the world, 14th tallest in Asia and 10th tallest in China. Site preparation required the demolition of several historical structures and the relocation of many shops in Cloth Alley.

Chicago's love for steel construction is apparent in the shape of its skyline. Most buildings that dominate the city's ceiling use steel as their primary construction material, and of the five tallest steel buildings in the world, three of them are situated in the city.

Another Skidmore Ownings and Merrill designed project, the John Hancock Centre is an example of Khan's trussed tube design. The trusses are clearly visible on the exterior of the building and are an obviously hint at the way Khan turned traditional skyscraper construction on its head.

The building was constructed over a five year period from 1965 by Tishman Construction, which went on to complete the World Trade Centre's twin towers in 1972 and 1973.

Completed in 2007, the Minsheng Bank is China's 12th tallest building and ranks as the world's 26th tallest. It has 68 floors, three of them underground, and it has a gross floor area of 110,000m³. The structure was built over a seven year period starting in 2001.

Beijing's tallest building is another Skidmore Owings and Merrill designed structure, and the fourth tallest constructed by contractors Arup.

The 74-storey tower is a remarkable accomplishment given that it sits on a geologically active area, making it one of the tallest buildings in any zone of high seismic activity. Proving that the building was capable of withstanding major seismic events was a considerable challenge, and Arup introduced a composite steel plate shear wall at the base of the tower to enable it to cope with the stress placed on it during an earthquake.

Completed in 2007 after a four-year construction period, the New York Times Tower is just a few centimetres short of the Chrysler Building's 319m stretch, and is home to the world famous newspaper.

It is also the tallest tower that contractor AMEC has ever built, and the largest that architects FX Fowle, and Renso Piano Building Workshop had seen through to fruition.

Though promoted as a green building, it's not LEED certified. The curtain wall is fully glazed with low-e glass, mechanised shades controlled by sensors reduce glare and cut HVAC load during key months, while more than 18,000 individually-dimmable fluorescent fixtures supplement natural light. The building has a raft of other energy saving measures.

It may only be the third tallest tower in New York, but many argue that the Chrysler Building and its art deco crown arches make it a far more attractive building than the rather stoic and utilitarian Empire State Building.

It certainly beat its rival to completion, ending construction in 1930 - a full year ahead of the Empire State Building. However, it's at least 60m shorter than the Empire State Building, and its highest floor is a staggering 100m below that of its rival.

It did, however, hold a few world records when finished - if only for a short time. It beat the Eiffel Tower to become the world's tallest structure in 1930, and it was also the world's tallest building. Both records were snatched by the Empire State Building in 1931.

Designed by Brooklyn born architect William Van Alen, it was the first man-made structure in the world to stand taller than 1,000ft, and it remains a defining landmark of New York's art deco era.

California's tallest building was designed to resist earthquakes of up to 8.3 on the Richter scale. At 73 storeys high, it is one of the most recognisable buildings in LA, and is often used in television shows and films to establish scenes depicting the city. The building's architects were Pei Cobb Freed and Partners, while Turner Construction, the company behind the Aon Centre in Chicago, built the structure.